1. Field of the Invention
This invention is directed to a temperature or thermal radiation sensor in the form of a metal-semiconductor film.
2. Description of the Prior Art
To measure cryogenic temperatures, the prior art teaches the use of such devices as bulk single crystal doped germanium thermometers. These generally have an exponential temperature dependence of resistance of the form e.sup.-E.sbsp.g.sup./T. Germanium devices can be useful down to about 1 degree K., and are in fact the only practical prior art means known to the present inventors for measuring temperatures below about 50 degrees K.
At somewhat higher cryogenic temperatures, say above 100 degrees K., variable resistance metal thermometers may be used. Also, thermocouple devices that consist of dissimilar metals may be used at the higher cryogenic temperatures. However, the prior art techniques generally do not allow for ready measurement over a wide cryogenic temperature range up to room temperature, that is, from about 1 degree K. to 300 degrees K. This is due to reduced sensitivities of the prior art devices in certain regions of this range. In addition, particularly with the metal resistance devices, such a large amount of power must be dissipated by the devices that the experimental conditions may be affected by the heat produced.
In addition, the prior art devices often have a significant hysteresis effect, making the measurements not readily reproducible. Finally, the relatively large mass of many prior art devices limits their ability to rapidly respond to temperature changes.
Clearly, it would be very desirable to have a device that could accurately and reproducibly measure temperatures over a wide range with high sensitivity and with fast response capability.